"That is good for the country, it needs strong leadership in uncertain times."

The Tories have been pushing the anti-hung parliament message hard over the last week, as they try to convince voters that a vote for Nick Clegg could create a dithering coalition government in uncertain times.

Mr Clegg demonstrated his confidence by visiting traditional Tory strong holds in the south-west of England.

His day was vastly improved by the news that the Labour-supporting Guardian was backing him. Most pundits now consider him the main challenger to Mr Cameron, in a sign of how disastrous Labour's campaign has become.

An above-average performance from Gordon Brown in the last debate failed to produce any improvement in his polling, and recent surveys suggest much of the Lib Dem surge is due to departing Labour voters.